The present invention relates to a novel batter system for application to a foodstuff for retail or food service type application.
Many foodstuffs, including meat, fish, fruits and vegetables, which are packaged in a frozen condition for retail sale or for use in a food service application, have a coating applied to a raw or partially-cooked food substrate. The foodstuff is heated and fully cooked for consumption by convection or microwave ovenizing or frying, depending on the foodstuff.
One such food coating is a tempura-like batter coating, which is a leavened batter. Such tempura batter coating generally comprises a primer layer consisting of an initial batter as a wetting and/or adhesive agent and/or a fine granular cereal crumb to precondition the surface to be coated. The tempura batter matrix generally contains flour, starches, proteins, leavening components, browning and flavouring agents.
A common problem with conventional tempura batters is that, while a crispy outer surface to the cooked batter can be obtained when reconstituting the food for consumption, an interface between the substrate and the crispy outer surface is formed which is wet, heavy and pasty, which detracts from the overall organoleptic quality or mouthfeel of the food product. This problem is particularly acute with food substrates which have a high moisture content, including fish, shellfish, fruit and vegetables. Often an even dispersion of the leavening gases is not achieved and gas cells coalesce to form pockets beneath the shell. In addition, the cooked shell of the coated substrate often has a rubbery texture, particularly when the foodstuff is oven cooked.
There is, therefore, a need for an improved tempura batter system which enables, upon cooking of a food substrate bearing the batter to an edible condition, the wet interface to be eliminated, the leavening gas to be evenly distributed and the coating to have a light and crisp eating quality, with a perception of a reduced layer of coating material.
In accordance with the present invention, there is provided an improved tempura batter system which enables significant improvements in the existing tempura batter systems to be achieved. The present invention involves improvements in both the primer layer or first pass system and the batter matrix layer.
When adhesion and/or improved coating coverage of the food substrate is desired, an underlying coating system is required. This system is optimized herein to maximize surface area while minimizing the contribution of mass to the overall coating, to optimize gelatinization and gelation and to manage water mobility in and through the layer. While the primer layer may comprise as much as about 20 to 30 wt % of the overall mass of a conventional tempura coating, it is contemplated herein to reduce this contribution to the overall mass to less than about 15 wt % of the overall coating mass. This may be achieved by providing a more dilute starch based batter and a finer granulation predust. The decrease in mass contribution and the choice of the first pass batter components and type of cereal predust, enables moisture release from the food substrate to and through the overlying tempura layer to be maximized and thereby contribute to decreased interface sogginess and vapour pressure build up.
A controlled gelling matrix is provided herein for the outer tempura coating in order to set the gas cell structure and permit effective penetration of heat during processing to thereby provide balancing of control of gelatinization, coagulation and gelation with cellular network expansion while managing water mobility and quantity in the batter system. As described in more detail below, a balancing of cereals, proteins, leavening system, fat and emulsifier is provided which produces effective gelatinization characteristics and a controlled formation of the outer shell.
A stabilized network of well-distributed, uniformly-sized gas cells throughout the matrix, which remain intact and do not coalesce or rupture within the batter matrix during continued mechanical agitation through mixing or application machinery and have controlled expansion during heating, permits a more effective heat transfer and affects positively the gelatinization, coagulation and water mobility characteristics of the batter system. As described in more detail below, these results may be achieved by employing an aerated and/or emulsified plastic fat or a semi-melted, emulsified plastic fat in addition to conventional leavening agents. Significant textural and/or visual benefits are derived by using such materials when compared to oils, fully melted plastic and powdered fats.
The coated food products provided in accordance with the present invention exhibit exceptional long-term freezer storage as compared to conventional tempura batter systems.
The batter composition provided herein may be employed in cohesion and/or adhesion style batter systems which act as an adhesive and/or cementing layer in which bread crumb material may be embedded.
In providing a suitable tempura batter system, a balance between cereal (flour, starches, dextrins etc.) components, added protein, the leavening system, fat and emulsifier is sought in order to minimize or even eliminate shelling characteristics of the batter. In this regard, an important component is the flour. Conventionally, soft wheat flour is employed as a significant component of the dry mix from which the batter is formed, percentages as high as about 80 to about 90% not being uncommon. We have found that higher quantities of soft wheat flour lead to a greater tendency to shell.
In the present invention, the quantity of soft wheat flour is maintained below about 75 wt % of the dry mix, preferably about 45 to about 65 wt % of the dry mix. Higher gluten-containing flours, such as hard wheat flour, produce undesirable shelling properties.
Starches are used herein to make up the bulk of the dry mix not provided by the decreased quantity of soft wheat flour. A variety of unmodified starch materials can be used, particularly native wheat starch, although other starches, such as corn starch, tapioca starch and potato starch may be employed, along with film-forming starch materials, such as modified corn starch. The latter component restores crispiness and crunchiness lost by decreasing the wheat gluten component through the use of a limited quantity of soft wheat flour in order to avoid shell formation.
The total percentage of unmodified starches and modified starches which are employed in the batter mix vary with the amount of soft wheat flour. In general, the total percentage of such starches is from about 10 to about 35 wt %, preferably from about 15 to about 30 wt %. The relative proportions of the unmodified starches and modified starches in the batter dry mix generally may vary from 0 to about 30 wt % unmodified starches, preferably about 5 to about 25 wt %, and from 0 to about 30 wt % modified starches, preferably about 5 to about 15 wt %.
In addition to starch augmentation, in order to further compensate for a reduction in the soft wheat flour component, protein material may be added to provide improved properties to the batter. The proteins generally are a mix of such materials to provide a variety of improved properties. The presence of the protein material adds colour to cooked food product. Gelling proteins assist with the enrobing qualities of the batter, overall emulsification of materials and maintaining the gases dispersed in the batter. Non-gelling proteins provide an enhanced crispness. Some of the protein materials which may be employed include egg albumin, soya proteins and modified milk proteins, such as sodium caseinate.
Quantities of total additional proteins may vary and the upper level of such materials generally is determined by cost considerations and may generally be about 3.5 wt %. Generally, both gelling and non-gelling proteins are used, generally in approximately equal weight proportions.
Frosted, freezer-burnt, dehydrated or reticulated are terms which are used to describe the undesirable lace-like surface appearance of many coated products that are fully fried to cook to an edible state. The tempura batter system of the present invention results in the improvements as described for an oven cook application. For such system, further modifications to the formulation are desirable to eliminate the frosting potential while retaining the desirable textural improvements.
The gelling and non-gelling isolates, as well as the shortening, are major contributors to the frosting phenomenon encountered with the fully-fried products. To a lesser degree, the emulsifier also contributes to this negative appearance attribute. As may be seen from the experimentation presented in Example 8 to 11 below, the gelling isolate and emulsifier are retained for their major structural and textural contribution, while the non-gelling protein sodium caseinate and non-gelling isolate have been removed and the level of shortening reduced. Additional dextrin and maltodextrin may be added to offset the reduction in shortening.
A leavening system comprising food-grade components which interact in the presence of water and/or heat to produce CO2 is employed in the batter dry mix. In particular, there is employed a combination of sodium bicarbonate and sodium acid pyrophosphate with an excess of the latter based on its neutralizing value, as may be found in some commercial baking powder blends. Usually neutralizing value percentages are used in coating batter systems. Higher amounts of sodium bicarbonate tend to enhance the overall browning characteristics of the batter.
Additional components of the leavening system are monocalcium acid phosphate and calcium lactate. The presence of excess sodium acid pyrophosphate, which may be up to about 50 wt % excess over the amount required to neutralize the sodium bicarbonate not reacted with the monocalcium acid phosphate, ensures that all the sodium bicarbonate is neutralized and further provides overall improved textural characteristics by decreasing the cohesiveness of the shell.
The presence of the monocalcium acid phosphate, which may neutralize about 15 to about 35 wt % of the sodium bicarbonate, ensures an initial rapid release of carbon dioxide from the sodium bicarbonate, not achievable by the slower reacting sodium acid pyrophosphate. The initial release of CO2 also aids in establishing gas cell nuclei and helps increase batter volume. Furthermore, use of monocalcium acid phosphate allows for use of elevated sodium bicarbonate levels in a batter, enhancing coloration during heating of the coating system without excessive puffing of the enrobed substrate. Puffing is reduced since the gas is formed prior to the gelatinization, coagulation and hardening of the enrobing matrix. The presence of the calcium lactate provides a controlled release of acid from the sodium acid pyrophosphate, helps mask the astringent flavour imparted by the excess sodium acid pyrophosphate and enhances the overall textural quality of the batter.
The overall quantity of leavening agents present in the dry batter mix may comprise about 1 to about 5 wt %, preferably about 1.5 to about 3 wt %, of the dry batter mix. The quantities (wt %) of the individual components of the leavening agents in the dry batter mix may comprise:
The combination of components described above helps provide effective gelatinization characteristics and a controlled formation of the outer shell from the batter mix.
In order to provide a stabilized network of well-distributed, uniformly-sized gas cells throughout the batter matrix, there may be employed an aerated plastic fat mixed in with the dry mix and the aqueous medium to form the batter. The aerated plastic fat appears to provide a stable dispersion of gas nuclei in the batter.
These nuclei assist in providing a uniform distribution of gas bubbles throughout the batter as the leavening system and steam expand their volume upon heating. An aerated fat having about a 175 to 225% overrun, which has a volume of approximately 2xc2xd to 3 times its non-aerated volume, suitably may be employed. Other degrees of aeration may be employed, as desired.
Suitable plastic fats which may be used preferably are those with relatively flat SFI profiles, preferably a profile of about 18 to 24% solids at 50xc2x0 F. and about 6 to 12% solids at 105xc2x0 F. One suitable plastic fat which may be used is non-emulsified xe2x80x9cCriscoxe2x80x9d brand all purpose shortening. It is most desirable for the plastic fat to be in its xcex2xe2x80x2 form, since the xcex2xe2x80x2 plastic form allows for most effective and stable aeration.
The quantity of aerated plastic fat which is employed in the dry mix varies from about 2 to about 15 wt % of the dry mix, preferably from about 3 to about 8 wt %.
An alternative component which may be added to provide a stabilized network of well-distributed, uniformly-sized gas bubbles is an emulsified plastic fat. An additional alternative is to provide the aerated plastic fat in an emulsified form. While many different emulsifiers are available, we have found that stearic and oleic polyglycerol esters, mainly of di-, tri- and tetra-glycerol length, lead to a desirable combination of a significant reduction in shelling and batter viscosity and a final batter texture which is crisp and short and a light and dry interface. Other emulsifiers tested, including mono- and di-glycerides, polysorbate 60, acid esters of mono- and di-glycerides, propylene glycol monoesters and sorbitan monostearate, which provide some variation in the properties of the batter, did not provide the desirable combination of improvements seen by employing the polyglycerol esters.
Where the plastic fat is emulsified, or where the plastic, emulsified fat is heated to about 40xc2x0 C. to achieve a semi-melted pourable mixture, without significant destruction of the xcex2xe2x80x2 crystal structure, the semi-melted plastic, emulsified fat may have the characteristics described above for the aerated fat.
The quantity of emulsified plastic fat used is generally less than about 15 wt % of the dry mix, preferably about 3 to about 8 wt %. The quantity of polyglycerol ester present in the emulsified plastic fat generally is up to about 10 wt %, preferably about 0.2 to about 0.3 wt %, of the dry mix.
The dry tempura batter mix provided in accordance with the invention is suspended in water along with dispersion of the plastic fat therein to form a batter for application to the food substrate coated with the primer. In general, the weight ratio of water to batter dry blend components and plastic fat (shortening) is used to provide a target viscosity. Such target viscosity generally varies from about 1500 to about 5000 cps, preferably about 2800 to about 3800 cps. Total coating pick-up values will vary depending upon substrate; desired levels to achieve finished product attributes and legal limitations for standardized foodstuffs. Coating contribution can typically range from about 20 to about 60 wt % of the coated product, but was found most desirable at about 40 to about 50 wt %.
The presence of at least one gum in the batter mix tends to increase the cold water viscosity of the batter, thereby enabling the batter mix to be diluted and still provide the target viscosity. In general, about 1 wt % or less of gum is added. A gelatinizing gum, such as methylcellulose, is preferable and may be used to assist in stabilizing batter shell expansion during processing and in the case of the full-fry application, reduce frosting potential.